Manufacture of cast iron



Patented Aug. 25, 1936 PATENT OFFICE MANUFACTURE CAST IRON Allan Leslie Norbury, Birmingham, and Edwin Morgan, Wylde Green, near Birmingham, England, assignors to The British Cast Iron Itesearch Association, Birmingham, England No Drawing. Application August 13, 1934, Serial No. 739,670. In Great Britain September 9,

Claims.

It is already known that improved qualities of grey cast iron can be obtained by reducing the size of the graphite flakes. One purpose of the present invention is to enable cast iron having 5 such a graphite structure to be produced commercially in a convenient and economical manner. Another purpose is to produce a white iron which is less liable to contain spots of grey iron than ordinary white iron, this being advantaeffect for the production of pigs or castings we 20 add to the materials from which cast metal is ordinarily made about 1% by weight of ferrosilicon-titanium containing about of tita-' nium. After mixing, air, orprefcrably carbon dioxide, is bubbled through the molten mass for a minute or two. Alternatively any other oxidizing gas may be used, or instead of using a gas any convenient oxidizing solid may be added to the melt, such as a carbonate or oxide. In certain cases the production of an oxidizing atmosphere in the melting furnace may be suificient to oxidize the titanium and give the desired result.

We are aware that it is already known to add titanium to cast iron. Also titanium or its compounds is often present as an unavoidable constituent. The mere presence of titanium in the iron is not, however, suflicient to achieve our obiect. The oxidation process is also necessary. By adding titanium to the melt and subsequently oxidizing it, we are able consistently to obtain the required qualities in a ready manner and without introducing undesirable complications in the technique of manufacture.

45 When a grey iron is required the silicon and other elements which affect the state of the carbon are in such quantities as are normally present in grey iron, and by our invention we are able toensure that thegraphite shall be in finely 50 divided flakes. But when white iron is required .the silicon and other elements which affect the condition of the carbon'must be in such quantitles as will cause the carbon to remain in the combined form. The application of the invention to white iron results in a structure which is devoid of spots of grey iron which are deleterious to the quality of the iron.

It is sometimes advantageous to blow hydrogen through the melt for one or two minutes after oxidation of the titanium. The eifect of the 5 hydrogen is to coarsen the graphite in the iron, this condition being desirable in some cases. By

our invention we are able to effect the necessary refinement of the iron, and subsequently if the fine graphite structure which results from our 10 invention is not desired, the coarser structure can be obtained by the use of hydrogen. Also hydrogen dissolved in grey cast iron tends to increase the amount of combined carbon in the solidified metal. Instead of hydrogen, hydrogen contain- 15. ing compounds such as steam and hydrocarbons may be used but hydrogen-is preferable. If too much hydrogen is dissolved in the molten iron it may cause blow holes but such excess hydrogen may be removed by allowing the molten metal to stand in contact with air or by blowing nitrogen or air or carbon dioxide through the molten metal.

Having thus described our invention what we claim as, new and desire to secure by Letters Patent is:-

1. In the manufacture of castiron, a process in which titanium is added to the molten iron and is subsequently oxidized.

2. In the manufacture of cast iron, a process 30, in which a titanium alloy is added to the molten iron and the titanium in the melt is subsequently oxidized. I

3. In the manufacture of cast iron, a process in which titanium is added to the molten iron, and an oxidizing gas is subsequently passed through the melt, until the titanium therein is' oxidized.

4. In the manufacture of cast iron, a process in which a titanium alloy is added to the molten 40 iron, and an oxidizing gas is subsequently passed through the melt until the titanium therein is oxidized.

5. In the manufacture of cast iron, a process in which titanium is added to the molten iron, and an oxidizing solid is subsequently added to the melt, for the purpose of oxidizing the titanium therein.

6. In the manufacture of cast iron, a process in which a titanium alloy is added to the molten iron, and an oxidizing solid is subsequently added to the melt for the purpose of oxidizing the tita nium therein.

'I. In the manufacture of cast .iron, a process in which titanium is added to the molten iron. 55.

the titanium in the melt is oxidized, and subsequently hydrogen is passed through the melt.

8. In the manufacture of cast iron, a process in which a. titanium alloy is added to the molten iron, the titanium in the melt is oxidized, and subsequently hydrogen is passed through the melt.

9. In the art of manufacturing cast iron, the steps of introducing titanium into the iron and subsequently oxidizing the titanium while the mixture is in a molten condition.

10. In the art of manufacturing cast iron, the steps of introducing titanium alloy into the iron and subsequently oxidizing the titanium while the mixture is in a molten condition.

ALLAN LESLIE NORBURY.

EDWIN MORGAN. 

